This invention relates to still cameras and to mechanisms therein for winding the film and cocking a striker member, and which operates the shutter when a manually operable shutter or striker operating button is depressed.
Such cameras commonly include clutching mechanism which, upon actuation of the film winding arm or film winding wheel thereof, engages both the striker cocking means and the film winding mechanism. In this connection, it is important that neither more nor less than the desired length of film is advanced, such that upon film exposure no overlapping of portions of pictures occurs in case of too little film transport, or in case of excessive film transport film material is not unnecessarily wasted. In modern pocket cameras of the cartridge type, the film advance is determined by metering apertures in the film spaced one film frame apart. A film sensing member scans the film to locate the next film metering aperture, and when the film sensing member falls into a metering aperture the film winding member becomes locked against further movement. Also, during the film winding operation, a shutter blade striker member is cocked. The termination of the film cocking and film winding operations will generally occur at different times, and so there must be provided a lost motion coupling to permit the manually operable film winding arm or wheel to continue its movement even though a cocking operation has terminated. Such lost motion mechanism has often comprised a slip clutch.
It is an object of the invention to provide a simpler lost motion mechanism than heretofore used for the purpose just described, which will retain the shutter striker member in the cocked position even when the film winding is continued. Another object of the invention is to provide a simple combined film winding and striker member cocking and release mechanism which operates with a reciprocating film winding member.
The slip clutching arrangement heretofore required so far is replaced in the invention practically by two force transmitting members, a driving gear and a gear segment which is provided with teeth only over a limited portion thereof and a dead motion portion. The dead motion portion always operates so that the driving connection between the driving gear and the gear segment is interrupted thereby in the shutter cocking driving direction. When the driving gear meshes with the gear portion of the gear segment, the gear segment and thus the striker member will be driven upon turning of the driving gear, preferably against the force of a biasing spring. When the gear segment is disengaged from the teeth of the driving gear because the dead motion portion is opposite the teeth of the gear, further driving of the striker member is interrupted automatically. Due to the fact that the last tooth of the gear portion, at the point of transition to the dead motion portion, is urged against a tooth of the driving gear under the action of a biasing spring, the striker member cannot snap back into the initial position provided the driving gear is prevented from moving in reverse direction of rotation. This is readily accomplished by a ratchet mechanism disposed between the film winder arm and the driving gear which allows the driving gear to be driven only in one direction (shutter cocking direction). To release the shutter and return the striker member into the initial position, it is sufficient to disengage the gear segment from the driving gear, which may readily be accomplished by urging the driving gear out of the plane of the gear segment, so that the aforementioned last tooth of the gear portion of the gear segment can no longer rest against a tooth of the driving gear and the biasing spring pulls or urges the gear segment back into its initial position. Thus, while this especially axial disengagement of the driving gear and gear segment has not yet occurred, the striker member will be maintained in the cocked position without use of a specific clutching arrangement.
On use of a one-way acting ratchet drive as a driving connection between the film winding arm and the driving gear, a simplified film winding system is provided by means of which the film may be wound in one direction only, for which purpose especially a circular or even a straight motion component is used as driving motion (upon actuation of the film winding arm).
Furthermore, due to the simple structure and small number of components, the invention results not only in a reduction of the manufacturing costs of the individual components themselves, but also in a reduction of the costs of assembly. Also, space-saving advantages result from this simpler construction.
Further embodiments and improvements of the invention are claimed in the subclaims and are apparent from the following description of the drawing. In this respect also, those further embodiments are highly advantageous and even independently inventive which relate to the combination of the shutter cocking mechanism with the film winding mechanism and the locking of the release push button in accordance with the invention.